Patent GB-538590-A (GB)
Title: Improvements in or relating to electromagnetic remote control devices
Filed: 1939-08-14
Abstract: 538,590. Change-speed control. DERUNGS, E. A. Aug. 14, 1939, Nos. 23380 and 23381. Convention dates, Aug. 18, 1938, and Feb. 20, 1939. [Class 80 (ii)] [Also in Group XXXV] A compound electromagnet, described for releasing a clutch and changing selector-controlled variable gears, comprises primary and secondary electromagnets each with one or more windings and having axially movable armatures coupled together with provision for relative movement, the arrangement being such that after energization of both electromagnets and complete or partial de-energization of the primary magnet, the armature of the primary magnet is maintained in the attracted position. The variable magnetic attraction of the armatures is compensated by a variable leverage device to transmit a constant torque. The magnet assembly, Fig. 1, comprises a primary magnet winding 3 fixed core 4 and armature 5, and secondary magnet windings 6, 6<1> fixed core 7 and armature 8, all mounted in a cylindrical casing 2 carried by fixed members 1. Clutch and dash-pot control levers 30, 19 are pivoted on the member 1, lever 19 being connected to the primary armature by links 17 and having rolling engagement with the clutch lever 30 on which rests a rod 9 passing loosely through the primary armature 5 and fixed to the secondary armature 8 which is connected to the gear control lever 46, the shaft 47 of this lever being of small cross section for a portion of its length so that it yields torsionally on meeting obstruction. When the windings are energized, armature 5 moves upwardly and operates the levers 19, 30 and the latter bears on rod 9 which carries up the secondary armature 8. When the primary armature has completed its stroke, the secondary armature is permitted to continue alone due to relative movement between rod 9 and the primary armature. The engagement of a selected gear is arranged to take place during the second portion of the movement of armature 8. Windings 6, 6<1> which may be in series or parallel are sufficient to maintain the armatures attracted. The clutch control lever 30 is yieldingly connected as shown to the main clutch lever 35, and cable 44 is provided for alternative pedal control of the combined clutch control and gear change mechanism if the electromagnetic control fails. When the magnets are de-energized. the clutch is engaged by the return movement' of the lever 30 the movement of which is damped as desired by the dash-pot 24. The variable leverage produced by the rolling action of levers 19, 30 is arranged in relationship to the varying magnetic pull on the armatures so that the clutch lever 30 transmits substantially constant torque. Arm 33 of the clutch lever may be adjustable as described with reference to Fig. 6 (not shown), and the secondary armature may be resiliently supported on the rod 9, Fig. 5 (not shown). Circuit arrangements, Fig. 7, of the complete control system. The manual selector lever represented by contact 70 is moved along a zig-zag path 71 to engage circuit preparing contacts 67, neutral position contact 69, and pairs of contacts 68, 68<1> for the forward and reverse gears. Normally the contact 70 is positioned mid-way between a contact 67 and a contact 68 or 69, e.g. at O. Assuming that it is desired to engage gear I, contact 70 is moved to the left over a contact 67 to engage contacts 68, 68<1>. On passing over contact 67, relay 74 operates contacts 75 which then remain closed until the gear is engaged. At contact 68, a circuit is closed for the selector magnet 64 of gear 1, and at contacts 68<1> circuits are closed for relay 79 and for windings 6, 6<1> of the secondary operating magnets, winding 3 of the primary operating magnet being energized by relay 79. Those operating magnets function as above described, and when gear operating lever 46 has effected engagement of the gear selected by magnet 64, a rod 86 in the selector box opens contacts 75 which de-energize the primary magnet winding 3. The secondary magnet windings 6, 6' which may be connected in series or parallel over switch 82, are however sufficient to maintain the armatures in the attracted position and are de-energized to engage the clutch if and when the driver has released the manual selector lever to restore contact 70 to a mid-way position. If the driver moves the lever directly to contacts 68, 68<1> without passing a contact 67, windings 6, 6' alone are energized but are not effective on the armatures. Modifications. In the circuit arrangement of Fig. 8 (not shown) the primary magnet also has two windings which are energized by relay 79 but the windings of the secondary magnet are not initially energized. The circuits of one of the primary windings and the windings of the secondary magnet are controlled by a switch operated by the rod 9 so that when the primary armature has completed its stroke, one of the primary windings is cut out and both windings of the secondary magnet are cut in so that the secondary armature completes its stroke and the clutch and gear operations are completed as before. Auxiliary switches may also be associated with the manual selector lever whereby during a gear change, clutch disengagement may be maintained as desired, and relay 74 alone is energized to disengage the clutch without moving the selector lever to change the gears, and also in case it is desired to change from gear III for example to neutral without running through the gears.